Pulling tool

ABSTRACT

A hydraulic pulling tool including inner and outer tubular members adapted for relative axial movement, hydraulic slips on the outer member, a pipe grapple on the inner member, indicator valve means which are automatically opened at the completion of each pulling stroke to release pressurizing fluid to indicate completion of the stroke and dump valve means operable by vertical manipulation of the drill string to complete the release of pressurizing fluid.

United States Patent 1191 Bernat et a1. 1

[ Aug. 14, 1973 PULLING TOOL 2,732,901 1/1956 Davis 166/98 2,806,534 9/1957 Potts 166/98 [751 Invemms Hem! f William 2,984,302 5/1961 Church 166/98 Murray, Boss1er C1ty, La. 73 Assignee: Tri-State 011 T661 1111111516166, 1116., Primary EXamineMJamIe-S A pp B si r City, L Attorney-J. Vincent Martin. W. Ronald Robins et a1. [22] Filed: June 21, 1971 ABSTRACT PP Nod 154,989 A hydraulic pulling tool including inner and outer tubular members adapted for relative axial movement, hy- 52 U.S. c1. 166/98 drauhc Slips on the Outer member, a p p g pp 9n [51] Int. Cl E21b 31/00 the inner member, indicator valve means which [58] Field of Search 166/98 tomatically Opened at the completion of each Pulling stroke to release pressurizing fluid to indicate comple- 5 R f r Cited tion of the stroke and dump valve means operable by UNITED STATES PATENTS vertical manipulation of the drill string to complete the 2,915,126 12 1959 POMS 166/98 release of pressunzmg fluld' 2,973,038 2/1961 Segelhorst 166/98 7 Claims, 10 Drawing Figures o o o o o o Patented Aug. 14, 1973 4 Sheets-Sheet 1 INVENTORS. HENRY A. BER/VAT BY WILL/AM K. MURRAY v Arm Patented Aug. 14, 1973 3,752,230

4 Sheets-Sheet 2 r/QQ INVENTORS. HENRY A. BERNAT BY WILL AM K MUKRAY WW/Miii/ PULLING TOOL SUMMARY OF THE INVENTION This invention relates to hydraulic pulling tools of the type used to pull liners, screens, stuck pipes, or other stuck objects from a well. More particularly, it relates to a hydraulic pulling tool including hydraulically actuated slips and valve means which are automatically opened at the completion of the pulling stroke to release the pressurized fluid, thereby signaling the completion of the stroke by the drop in hydraulic pressure and simultaneously releasing the hydraulic slips so that the tool may be raised in preparation for taking another stroke. The invention also includes a dump valve which will be alternately opened and closed on alternate up and down reciprocations of the tubing string.

A principal object is to provide an improved pulling tool of the type described which'is hydraulically operated.

Another object is to provide a pulling tool composed of telescopically engaged members movable relative to each other by hydraulically operated means, the outer member having hydraulically operated anchor means for engagement with a well casing and the inner member having grapple means on its lower end for connection to an' object to be pulled upwardly in the well.

A further object is to provide such a tool wherein the same hydraulic pressure is employed for actuating the anchor means and for operating the tool.

A more specific object is to provide a pulling tool of the character described, which includes valve means arranged to automatically open at the completion of the pulling stroke to release the pressurizing fluid thus simultaneously signaling the completion of the stroke by a drop in the hydraulic pressure and effecting release of the hydraulically actuated well wall-engaging anchor means.

Another object is to provide a pulling tool that may be operated in directional well bores which requires a minimum of rotational manipulation to control the action of the tool. This is desirable as it is difficult to control limited rotational movement in a directional well due to the high friction between the well bore and the pipe.

A still further object is to provide such a tool having a valve means which may be operated by vertical movements of the tubing string so as to fully release pressurizing fluid in the event the automatically actuated valve means fails to do so and to drain the tubing when retrieving the tool and fish from the well bore.

The pulling tool herein disclosed is an improvement over the pulling tools shown in U.S. Pat. Nos. 2,732,901, 2,984,302 and 2,915,126.

DESCRIPTION OF THE DRAWINGS AND THE PREFERRED EMBODIMENTS These and other objects and advantages of the invention will become apparent from the drawings, the specification and claims. In the accompanying drawings which illustratethe preferred embodiment of the invention, and wherein like numerals indicate like parts;

FIG. 1 is a diagrammatic view with portions shown in section and illustrating the various components of the tool intheir respective positions as the tool is run into the well and about to be engaged with a stuck pipe;

FIG. 2 is sequential to FIG. I showing the tool engaging the stuck pipe and with the anchor means set in preparation for taking a pull;

FIG. 3 shows the tool at the completion of its pulling stroke and with slips retracted;

FIG. 4 is a view in elevation, with portions shown in section, of the lower end of the preferred form of pulling tool connected to a stuck pipe;

FIG. 5 is a continuation of FIG. 4 illustrating the next uppermost portion of the pulling tool including a piston and cylinder;

FIG. 6 is a continuation of FIG. 5 illustrating the portion of the pulling tool located above that shown in FIG. 5 including a second piston and cylinder;

FIG. 7 is an upward continuation of FIG. 6 illustrating the indicator valve means and anchor means;

FIG. 8 is a continuation of FIG. 7 and comprises an elevational view, with portions shown in section, of the lower portion of the dump valve used in the preferred form of the pulling tool;

FIG. 9 is a continuation of FIG. 8 showing the upper portion of the dump valve; and

FIG. 10 is a diagrammatic view illustrating the operation of the valve of FIGS. 8 and 9.

The general construction and method of operation of the tool may best be understood by reference to FIGS. 1 through 3 where the tool and its operation are illustrated diagrammatically. There is shown a pulling tool 10 supported by pipe string 11 within a well casing 12 and disposed above a section of pipe, or fish, 13 which is stuck in the well bore. The pulling tool comprises generally a tubular outer shell or body A and a tubular inner member or mandrel B which are arranged for relative telescoping movement. The lower end of the mandrel is preferably hexagonal and engages a hexagonal sleeve on the lower end of body A so that while the mandrel and body may slide freely relative to each other they will rotate together. The body A carries well-wall engaging anchor means E which are hydraulically actuated slips. When actuated, the slips move outward to anchor the pulling tool firmly to well casing 12. The mandrel B carries at its lower end grapple means G for engagement with the fish I3.

Annular seals S carried by the body A seal between the body and mandrel B to define hydraulic cylinders the surface solely by vertical manipulation of the pipe string 11.

In operation of the hydraulic pulling tool 10, it is run into the well casing as shown in FIG. 1 and the grapple G is engaged with the fish 13. Next, pressurizing fluid is supplied to the tool to actuate hydraulic slips (FIG.

2) and to move the pistons P upward in hydraulic cylinders C, thereby moving mandrel B and fish l3 upward in the well bore (FIG. 3). When the pistons P reach the upper end of cylinders C so that the pulling stroke is completed, indicator valve I opens automaticallyv to release pressurizing fluid in the tool. When the pressure has decreased sufficiently, slips E will retract (FIG, 3)

and the tool may be raised or reextended, in preparation for the taking of another stroke.

When the fish 13 is freed, its weight is supported by mandrel B. As explained more fully hereinafter, this situation may cause indicator valve I to re-close before pressure in the tool has dropped sufficiently to release the slips E. Therefore, the dump valve D is provided to effect full release of fluid pressure when indicator valve I fails to do so.

The details of construction of the preferred form of the hydraulic pulling tool of the present invention are shown in FIGS. 4-10, with FIGS. 4-7 showing the pulling tool and FIGS. 8-10 showing the dump valve.

Referring now to FIGS. 4-7, the tubular outer shell or body A comprises multiple sections threadedly connected with the seal means S, to seal between the body and mandrel B, being tubular sections of reduced inner diameter (FIGS. 5 and 6) and having inner and outer resilient seal elements 14 to provide a liquid-tight seal. The three seals S define, with the mandrel B, two hydraulic cylinders C. A port 15 is provided in the body A near the top of each cylinder C to provide fluid communication between the portion of cylinder C above the piston P and the well annulus. An additional port 16 (FIG. 7) is provided in body A in connection with the indicator valve Ias hereinafter explained.

The mandrel B is similarly comprised of multiple tubular elements threadedly connected, with the two pistons P (FIGS. 5 and 6) being tubular members of enlarged outer diameter and having resilient seal elements 17 thereon to provide a liquid seal with the inner surface of body A. A port 18 is provided in the mandrel B below each piston P to place the lower portion of each hydraulic cylinder C (below piston P) in fluid communication with the bore 19 of mandrel B.

The mandrel B includes an upper section 20 of reduced outer diameter and a lower section 21 of enlarged outer diameter with upwardly and inwardly tapering cam surface 22 (FIG. 6) being formed between the two. As hereinafter explained, the purpose of cam 22 is to actuate indicator valve I at the completion of the pulling stroke.

The uppermost end of mandrel B has splines 23 (FIG. 7) which are slidable in the bore 24 of tool body A. The interstices between splines 23 permit pressurizing fluid access in the annulus between the ad of mandrel B and the i.d. of body A so that pressurizing fluid may reach the indicator valve I.

The lower end of the mandrel B is hexagonal as at 25 (FIG. 4) and engages hexagonal sleeve 26 on. body A so that while the mandrel B and body A may slide longitudinally relative to each other, they will rotate together so that, as hereinafter explained, the grapple G may be engaged with the fish 13 by rotation of the pipe string 11. Hexagonal extension 25 of mandrel B has in its bore a valve seat 25a on which may be seated a ball valve 25b when it is desired to pressure up the tool.

At the lowermost end of the mandrel B is a grapple means G for engagement with the fish 13 which is to be pulled upwardly in the well bore. The particular grapple means illustrated is a threaded pin for engagement which the threaded box portion 13a of fish 13. However, it is understood that any conventional grapple means may be used and that the fish 13 may have no threads, as for example where a pipe is broken off.

Hydraulically actuated anchor means E are provided on the body A for anchoring the body to the well casing during the pulling operation. As shown in FIG. 7, multiple longitudinal slots 27 are provided in the body A. Disposed within each slot is a slip holder 28 to which a slip shoe 29 is connected by screws 30. The slip holders are urged radially inwardly toward a retracted position by compression springs 31 which bear at their outer ends against slip keepers 32 attached to body A with screws 33. Behind each slip holder 28 is a resilient packer or seal 34 which prevents the escape of pressurizing fluid around the holders. The slips are actuated by the buildup of hydraulic pressure within the bore of body A which urges the slips outwardly, compressing springs 31 until the slip shoes contact the well casing 12, thereby anchoring the body A to the casing. When fluid pressure is decreased, the springs 31 will return the slips to their retracted position.

The indicator valve means I is shown in detail in FIG. 7. It includes a valve sleeve 35 mounted between the mandrel and body and having seals 36 and port 37. With the valve in the position shown in FIG. 7, the seals 36 cut off communication between ports 37 in the valve and ports 16 in the body A so that the valve is closed. Compression spring 38 urges the valve sleeve upward toward an open position with ports 37 and 16 in register, but latch 39 pivotally mounted on the valve sleeve by pin 40 engages the upper end of a recess 41 in the inner wall of body A and retains the valve sleeve against upward movement. Latch 39 has at its lower end a roller 42 which acts as a cam follower responsive to tapered cam surface 22 (FIG. 6) on mandrel B. As will be later described, as the tool approaches the completion of its pulling stroke, cam surface 22 will engage roller 42, pivoting latch 39 about pin 40 in a counterclockwise direction, freeing the latch from recess 41, and thus releasing the valve sleeve 35 to move upward to an open position responsive to spring 38.

An additional valve means, the dump valve D (FIGS. 8-10) is also provided to release pressurizing fluid within the pulling too].

As shown in FIG. 8, the dump valve, indicated generally at D, includes an elongate tubular member 43 mounted for limited longitudinal movement within the bore of pulling tool body A. The bore 44 of tubular member 43 forms a fluid passageway through which the pressurizing fluid for the pulling tool passes. Seals 45 at each end of tubular member 43 provides a sliding,

fluid-tight seal between it and the bore of body A at the lower end and mandrel on the upper end. Formed integrally with tubular member 43 is a valve sleeve 46 having ports 47 therein whichare in communication with the fluid passageway, or bore, 44 of member 43. When the valve is in its raised or open position, ports 47 are adapted to coact with ports 48 in the body A to provide a passageway through which the pressurizing fluid within the pulling tool may escape into the well annulus. However, when the valve is in its lowered position as shown in FIG. 8, seals 49 on valve sleeve 46 block communication between ports 47 and 48 so that I the valve is closed.

Valve D is retained'in its open or closed position by coil spring 50, which urges the valve upward, and by valve positioning lugs 51 on tubular member 43 which seat in either shallow or deep valve locating recesses 52 and 53, respectively, formed in sleeve 58 on the inner surface of body A. If the valve positioning lugs 51 are seated in the shallow valve locating recesses 52 (as shown in FIG. 8), then valve D is retained in its lower or closed position. Conversely, if valve positioning lugs 51 are seated in deep valve locating recesses 53, then the valve will be in its raised or open position with ports 47 in valve sleeve 46 in communication with ports 48 in tool body A. The movement of valve positioning lugs 51 between the shallow and deep valve locating recesses is controlled by valve actuating lugs 54 on valve mandrel 55 (FIG. 9). Mandrel 55 is threadedly connected to top sub 56 which is connected to the pipe string 11 and is adapted to move vertically with the pipe string. Mandrel 55 is retained against rotation relative to body A by vertical splines X which slide in vertical slots Y in the body A. (FIG. 9).

The operation of valve D and the interaction between valve actuating lugs 54, valve positioning lugs 51 and valve locating recesses 52 and 53 may best be understood by reference to FIG. wherein the parts and their operation are indicated diagrammatically. For

purposes of illustration, only one valve positioning lug 51 is indicated in FIG. 10, although multiple lugs are contemplated in the actual tool. The lugs and recesses are so arranged that all of the lugs 51 will simultaneously seat in either the shallow or the deep valve locating recesses.

In operation, with the valve closed as shown in solid lines in FIG. 10, the port 47 in valve sleeve 46 is out of registry with port 48 in body A, and seals 49 block fluid communication through the narrow annulus between the valve sleeve and the body. When it is desired toopen the valve, the operator simply lowers and then raises the pipe string. As the pipe string is lowered, valve actuating lugs 54 engage and depress valve positioning lugs 51 which move the valve D downward against the action of spring 50. When the valve positioning lugs 51 reach the nadir 57 of shallow valve 10- cating recess 52, the coacting slanted surfaces on the valve actuating lugs 54 and valve positioning lugs 51, under the urging of spring 50, will cause the valve D to rotate slightly about its longitudinal axis and snap upward until valve positioning lugs 51 seat in the next set of valve locating recesses, which would be the deep valve locating recesses 53. Valve positioning lugs 51 will seat fully in recesses 53 as the pipe string and valve actuating lugs 54 are raised. This position is indicated in'the dotted lines in FIG. 10. In this position, the ports 47 in valve sleeve 46 are in registry with ports 48 in body A so that the valve is open. This would permit escape of the pressurizing fluid into the well annulus. Another down and up reciprocation of the tubing string would cause the valve to again depress, rotate slightly in the same direction and seat in the next set of shallow valve locating recesses so that the valve would be closed.

A major advantage in the dump valve D of the present invention over prior art valves is that it may be operated merely by up and down movements of the supporting string and is adapted to be alternately open and closed on alternate reciprocations of the tubing string. This provides a valve which is extremely simple to operate, highly reliable, and which avoids the necessity for complex vertical and angular movements of the tubing string which are necessary to operate many of the prior art valves.

Also it should be noted in FIG. 8 that the o.d. of tubular member 43 above-valve sleeve 46 is less than that below valve sleeve 46 so that the annular area 43a (created by the wall thickness of the upper end of member 43) is less than the area 43b (created by the wall thickness of the lower end of 43). Since both areas 430 and 43b are exposed to the same fluid pressure within the bore of the tool, the difference in their areas results in a net upward force on the valve member which complements the action of the spring 50.

The primary usefulness of the dump valve D is at the completion of the pulling operation to fully drain the pipe string 11 as explained more fully hereinafter.

The operation of the pulling tool is as follows: The tool is run into the well at the end of pipe string 11, preferably with both valve means I and D closed so that fluid may be circulated through the tool as it is run into the well. 1

As the pulling tool reaches the stuck pipe or fish 13, the pipe string 11 and thus the body A and the mandrel B, are rotated to engage the grapple G with the threaded box end 13a of stuck pipe 13. It is understood that the use of other grapple means is also contemplated which may not require rotation for engagement with the fish 13. Next, an upward pull is taken on the pipe string 11 to see if the fish will dislodge easily. This upward pull also serves to close and latch the indicator valve means I (which will have been opened by the upward movement of mandrel 13 during engagement of the grapple G with the fish 13). As the body A moves upward relative to mandrel B, valve sleeve 35 will also tend to move upward responsive to spring 38 which is carried by body A. However, once the upper end of valve sleeve 35 contacts the lower ends of splines 23 on mandrel B, further upward movement of the valve sleeve is stopped and continued upward movement of body A acts to compress spring 38, moving ports 37 and 16 out of alignment and thus closing the valve. As recess 41 in body A moves upward, it is engaged by latch 39, thus locking the valve means I in its closed position.

The pulling tool is now ready to receive pressurizing fluid. To seal off the lower end of bore 18 in mandrel B, a ball 25b is dropped from the surface through pipe string 11 to engage seat 250 in the lower end of mandrel B (FIG. 4). Next, pressurizing fluid is pumped into the tool through pipe string 11 and is present throughout that portion of the bore of body A above the uppermost body seal means S (FIG. 6), as well as in the bore of mandrel B. As the fluid pressure increases, it acts first to expand the hydraulic anchor means E until they engage the inner wall of casing 12. At this point, the tool will appear as shown diagrammatically in FIG. 2 with slips E expanded, valve means I closed, and with pistons P at the lower end of hydraulic cylinders C. A further increase in fluid pressure will cause the pistons to begin moving upwardly in their cylinders with pressurizing fluid entering the cylinders C below the pistons P through ports 18 (FIGS. 5 and 6), and with well fluid exiting from the cylinders C above the pistons P through ports 15 into the well annulus. Since the body A is anchored to casing 12 by anchor means E, this upward movement of the pistons and mandrel exerts a strong upward pull on the stuck pipe 13 through grap- -ple means G, causing it to move upwardly with the mandrel B.

As the mandrel B moves relatively upward, roller 42 on valve latch 39 will roll along the outer surface of the upper portion 20 of mandrel B until it engages the tapered cam surface 22. As explained above, once the roller 42 engages cam surface 22, it pivots latch 39 about pin 40 causing the latch to disengage from recess 41. Valve sleeve 35 then snaps upward responsive to spring 38 into an open position where body port 16 and valve port 37 are in alignment. With valve means i open, pressurizing fluid escapes from the tool into the well annulus, resulting in a rapid drop of fluid pressure within the tool. This drop in pressure can readily be monitored at the well surface giving clear indication that the pulling tool has completed its stroke and signaling the operator to turn off the fluid pump. At the same time, the drop in pressure deactuates hydraulic slips so that compression springs 31 can retract the slips into the body. The tool is shown in this position in FIG. 3 with the slips retracted, valve means I open, and pistons P at the upper end of hydraulic cylinders C. The stuck pipe 16 has been moved upwardly a distance equal to the pulling stroke of the tool. Another upward pull may now be taken from the surface with pipe string 11 to re-extend the tool and re-latch valve 1 so that another pulling stroke may be taken, and the cycle repeated until stuck pipe 16 is freed, at which time it may be lifted to the surface and removed.

During the pulling stroke on which the fish 13 is Finally freed, it will be lifted upward in the well bore by mandrel B as the tool completes its full stroke and will therefore exert a downward pull on mandrel B due to its weight. Then, as the pressurizing fluid bleeds out of the tool through indicator valve I, the combined weight of the fish and mandrel B may move the mandrel downwardly and relatch valve I before the pressure has dropped sufficiently for the anchor means E to retract. This would lock the tool in the well. However, this is prevented by the provision of dump valve D which may be actuated from the surface to fully release pressurizing fluid within the tool. Also, dump valve D may be left open as the string is pulled so that all fluid will drain from the tubing string. The dump valve D additionally functions as a desirable safety device, providing means for releasing the internal fluid pressure in the event the automatic valve I fails to do so. Such a situation might arise, for example, when the pulling tool is unable to dislodge the stuck pipe and therefore cannot complete a pulling stroke. in this event, the automatic valve 1 would not be actuated and, if there were no other means for releasing the fluid pressure within the tool, the hydraulic slips would remain engaged with. the well casing, making it very difficult to retrieve the pulling tool itself. However, with the dump valve D, the pressure can readily be released so thatthe slips would retract. Then the pipe spearcan be disengaged from the stuck pipe and the pulling tool retrieved.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

l. in a hydraulic pulling tool including a cylinder having hydraulic anchoring means for anchoring said cylinder within a pipe, a mandrel slidable in said cylinder and having a piston secured thereto and a grapple on the lower end thereof, and .means for conducting hydraulic fluid to said anchoring means to set same and to said piston to move saidmandrel upward relative to said cylinder to effect a pulling stroke, the improvement comprising,

indicator valve means in said cylinder adapted to control the release of said hydraulic fluid,

resilient means associated with said indicator valve means urging said valve means toward an open position,

latch means associated with said indicator valve means to selectively retain said indicator valve means in a closed position, and

means on said mandrel adapted to coact with said latch means at the completion of said pulling stroke to open said valve means and release said pressurizing fluid.

2. The pulling tool according to claim 1 wherein dump valve means are additionally provided to control the release of pressure fluid,

said dump valve means including means actuated by vertical reciprocation of the supporting pipe string for opening and closing said dump valve means.

3. The pulling tool according to claim 2 wherein said dump valve means includes resilient means urging said dump valve toward an open position.

4. The pulling tool according to claim 2 wherein said dump valve includes means for utilizing the pressuriz' ing fluid within said tool to urge said dump valve means toward an open position.

5. A pulling tool comprising inner and outer tubular members telescopically connected for relative axial movement;

longitudinally spaced annular seal means mounted on the respective tubular members to seal between said members;

grapple means carried by said inner member connectible to an object to be pulled upwardly in the well bore;

hydraulically actuated casing wall engaging anchor means carried by said outer member;

means for introducing a pressure fluid into the bore of said outer member to act upon and actuate said anchor means;

means for introducing a pressure fluid between said tubular members between said spaced annular sealed means to produce a relative axial movement of said tubular members which comprises a pulling stroke;

indicator valve means mounted in said outer member and adapted to control the release of pressure fluid, said indicator valve means being normally closed during the pulling stroke,

means on said inner member adapted to coact with said indicator valve means as the pulling stroke is completed to open the valve means and release the pressure fluid acting on said anchor means and on said seal means whereby said anchor means is released; and

dump valve means carried in said outer member adapted to control the release of said pressure fluid,

said dump valve means being normally closed during the pulling stroke and being movable between open and closed positions by vertical reciproc'ations of a pipe string supporting said pulling tool,

said dump valve means including means normally urging said dump valve means toward an open position whereby said dump valve means may be maintained in open position while said pulling tool and supporting pipe string are removed from the well. 6. A hydraulic pulling tool comprising,

a tubular body adapted to be supported within a well bore by a pipe string;

a tubular mandrel slidable within the bore of said body;

longitudinally spaced annular seals on said body to seal between said body and said mandrel to form hydraulic cylinders;

pistons on said mandrel slidable in said cylinders;

grapple means on said mandrel connectible to an object to be pulled upwardly in the well bore,

hydraulically actuated anchor means on said body for anchoring said body within the well bore;

means for introducing a pressure fluid into the bore of said body to act upon and actuate said anchor means;

means for introducing a pressure fluid into said cylin-' ders below said pistons to movesaid pistons upwardly in said cylinders to produce relative axial movement between said body and said mandrel which comprises a pulling stroke;

indicator valve means in said body adapted to control the release of said pressure fluid, said indicator valve means including,

a valve sleeve slidable in the bore of said body and having a port adapted to coact with a port in said body to release said pressurizing fluid,

resilient means carried by said body urging said valve toward an open position,

latch means carried by said valve sleeve to selectively retain said valve sleeve in a closed position,

means on said mandrel adapted to automatically release said latch means at the completion of a pulling stroke to permit said resilient means to open said indicator valve to release said pressurizing fluid; and

dump valve means carried in said outer member adapted to control the release of said pressure fluid,

said dump valve means being normally closed during the pulling stroke and being movable between open and closed positions by vertical reciprocations of said pipe string.

7. The pulling tool according to claim 6 wherein said dump valve means includes means normally urging said dump valve means toward an open position. 

1. In a hydraulic pulling tool including a cylinder having hydraulic anchoring means for anchoring said cylinder within a pipe, a mandrel slidable in said cylinder and having a piston secured thereto and a grapple on the lower end thereof, and means for conducting hydraulic fluid to said anchoring means to set same and to said piston to move said mandrel upward relative to said cylinder to effect a pulling stroke, the improvement comprising, indicator valve means in said cylinder adapted to control the release of said hydraulic fluid, resilient means associated with said indicator valve means urging said valve means toward an open position, latch means associated with said indicator valve means to selectively retain said indicator valve means in a closed position, and means on said mandrel adapted to coact with said latch means at the completion of said pulling stroke to open said valve means and release said pressurizing fluid.
 2. The pulling tool according to claim 1 wherein dump valve means are additionally provided to control the release of pressure fluid, said dump valve means including means actuated by vertical reciprocation of the supporting pipe string for opening and closing said dump valve means.
 3. The pulling tool according to claim 2 wherein said dump valve means includes resilient means urging said dump valve toward an open position.
 4. The pulling tool according to claim 2 wherein said dump valve includes means for utilizing the pressurizing fluid within said tool to urge said dump valve means toward an open position.
 5. A pulling tool comprising inner and outer tubular members telescopically connected for relative axial movement; longitudinally spaced annular seal means mounted on the respective tubular members to seal between said members; grapple means carried by said inner member connectible to an object to be pulled upwardly in the well bore; hydraulically actuated casing wall engaging anchor means carried by said outer member; means for introducing a pressure fluid into the bore of said outer member to act upon and actuate said anchor means; means for introducing a pressure fluid between said tubular members between said spaced annular sealed means to produce a relative axial movement of said tubular members which comprises a pulling stroke; indicator valve means mounted in said outer member and adapted to control the release of pressure fluid, said indicator valve means being normally closed during the pulling stroke, means on said inner member adapted to coact with said indicator valve means as the pulling stroke is completed to open the valve means and release the pressure fluid acting on said anchor means and on said seal means whereby said anchor means is released; and dump valve means carried in said outer member adapted to control the release of said pressure fluid, SAID dump valve means being normally closed during the pulling stroke and being movable between open and closed positions by vertical reciprocations of a pipe string supporting said pulling tool, said dump valve means including means normally urging said dump valve means toward an open position whereby said dump valve means may be maintained in open position while said pulling tool and supporting pipe string are removed from the well.
 6. A hydraulic pulling tool comprising, a tubular body adapted to be supported within a well bore by a pipe string; a tubular mandrel slidable within the bore of said body; longitudinally spaced annular seals on said body to seal between said body and said mandrel to form hydraulic cylinders; pistons on said mandrel slidable in said cylinders; grapple means on said mandrel connectible to an object to be pulled upwardly in the well bore, hydraulically actuated anchor means on said body for anchoring said body within the well bore; means for introducing a pressure fluid into the bore of said body to act upon and actuate said anchor means; means for introducing a pressure fluid into said cylinders below said pistons to move said pistons upwardly in said cylinders to produce relative axial movement between said body and said mandrel which comprises a pulling stroke; indicator valve means in said body adapted to control the release of said pressure fluid, said indicator valve means including, a valve sleeve slidable in the bore of said body and having a port adapted to coact with a port in said body to release said pressurizing fluid, resilient means carried by said body urging said valve toward an open position, latch means carried by said valve sleeve to selectively retain said valve sleeve in a closed position, means on said mandrel adapted to automatically release said latch means at the completion of a pulling stroke to permit said resilient means to open said indicator valve to release said pressurizing fluid; and dump valve means carried in said outer member adapted to control the release of said pressure fluid, said dump valve means being normally closed during the pulling stroke and being movable between open and closed positions by vertical reciprocations of said pipe string.
 7. The pulling tool according to claim 6 wherein said dump valve means includes means normally urging said dump valve means toward an open position. 